Actually, I feel the particular streak in question mentioned in the thread opener could indicate a CO2 event rather than a direct water event, although water may be indirectly involved in the trigger mechanism.

First, I am rather disinclined to see the bright streak as a deposit. Rather, I see it as a cleaning event where darker overlying dust has been blown clear of a brighter albedo underlying surface. However, after this I am more inclined to agree with the authors that this particular event is more a dry event than a wet event. It seems even less likely to be a mudslide. The displaced dust resides in a darker streak that is to one side and a little downslope of the brighter albedo. One may need to turn up the contrast in the IAS viewer to see the darker streak.

When looking at the highest resolution of the HiRise image, one can see the upper parts are scoured clean while some darker dust remains trapped in the valleys within the bright streak. This is somewhat counter to the expectation of a bright material deposit via liquid. Yet the event appears too violent to just be a dry dust avalnche. It appears a more violent trigger is needed to sustain a flow over such a rough downhill terain. One would expect a quicker termination and a pooling of dust in the ravines within the bright streak if it is a mere avalnche where only the coefficent of friction was just surpassed to start the flow. Such a flow would terminate sooner than is observed. There are other supposed BGDs where pooled dust can be seen at the base of the new bright streak, but here the dust has been displaced to a new dark streak.

Now one could go with the orginal Malin idea that released water would vigorously evaporate on the way downhill which could raise the dust and reemplace it into the darker streak, but then one would need a source for a rather large amount of water to accomplish the feat although it would be less than what would be needed for a wet event rather than an evaporation event.

But one could also consider a CO2 event where surface frozen CO2 was emplaced between thin layers of blown in sleet water ice which sealed the CO2 as though it were a CO2 sandwich between slices of water ice. The cold temperaures cause the water ice to expand to compress the CO2. When tempratures rise, the CO2 turns to a pressurised gas trapped within the ice slices. Should the temperature rise enough to compromise the water ice confinement, this failure point forms the failure apex where the CO2 can excape its cage and fluidize the dust for downslope transport.

I can't say for sure that this is what happened, but the scenario fits well with the visual evidence at the highest details and contrast and remains sympathectic with the newest model. The main difference is the opinion that there is no bright material deposited but rather darker material removed and emplaced downslope into another streak.